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Fundamental Mastering Tools and The Primary Colors of Mastering
Published in Evren Göknar, Major Label Mastering, 2020
DA and AD converters (Figures 4.1–4.5) usually include onboard level adjustments for calibrating the chosen operating reference level for the mastering studio. This calibration correlates digital decibels full scale (dBFS) levels with analog voltage readings and the VU meter so that lower dBFS levels (adjusted at the DA converter to 1.23V = 0VU = +4dBu) raise quieter more dynamic source files for a more robust level through the mastering system. The reference level calibration is accomplished by playing a 1kHz tone at the PBDAW at the selected dBFS level (usually −14dBFS), verification of voltage level at DA conversion (1.23V), then to the AD converter, the RDAW and post RDAW DA converter for end-of-chain monitoring. Reference level calibration is critically important for establishing headroom (region of signal between a nominal level and clipping—often 0dBFS digitally and +24dBu analog) in a mastering system, and is usually calibrated as one of three options (Table 4.1).
Moving-Magnet Inputs
Published in Douglas Self, Small Signal Audio Design, 2020
Groove noise on a microgroove disc is between -70 and -64 dB (A-weighted) below the nominal level, as noted earlier. Later in this chapter, you will see that a humble 5534A in a single amplifier stage gives a signal/noise ratio of -81.4 dBA (A-weighted) without load-synthesis, which is only 3.1 dB worse than a wholly noiseless amplifier. The groove noise will therefore be 11.4 dB above the amplifier noise; even if we had magic noiseless electronics, the total noise level would only drop by 0.33 dB. This would be an argument against striving for low-noise amplifiers if it was an expensive pursuit, but it is not. All you need is a cheap opamp and a little ingenuity.
Recording and reproduction
Published in Michael Talbot-Smith, Audio Engineer's Reference Book, 2013
Andy Wilson, Kenneth Gundry, Jan Arts, Jan Maes, Douglas Ford, Peter Skirrow
Specifications of noise performance should always be relative to nominal level. It is lamentable that most specifications for noise on CD players mention no noise weighting, and are relative to peak level, without mention of the 18 dB of headroom normally employed on CD to avoid harsh clipping. A true CCIR-weighted figure relative to nominal level allows much fairer comparison with other devices, as will be shown later, and this is another good reason why the nominal level concept makes sense, since headroom is always increased at the expense of signal-to-noise ratio, which is arguably more important than dynamic range (a confusing term best avoided).
Braking performance of friction materials: a review of manufacturing process impact and future trends
Published in Tribology - Materials, Surfaces & Interfaces, 2023
Nesrine Hentati, Fatma Makni, Riadh Elleuch
From the above, all efforts already made and all proposed works to investigate the formulation and process conditions aimed to achieve comfort and safety for drivers and passengers with reasonable cost of manufacturing. To fulfil this target, friction materials used either for brake or clutch should possess certain properties and performance characteristics that depend on material formulation [177] and manufacturing process. Therefore, scientists should not be restricted to study only friction materials for brake pad. A more attention should also be paid on manufacturing process of friction materials intended for clutch facings whose required performances, formulation and process are similar to that used for brake linings [178]. In a recent study [179], the hardness was investigated as it was considered as the major root cause for the failure of clutch operation. The studied organic clutches were elaborated, as organic brake pad, according to the usual procedure: mixing raw materials, preforming, hot pressing and heating. In their work, researches tried to optimize the process parameters in order to maintain the hardness value of clutch facing at a nominal level to avoid noise during service, using statistical control tools like Histogram, flow chart and trend analysis. They found a strong positive correlation between hot pressing parameters and hardness (harness and pressure, hardness and temperature, hardness and duration). Therefore, additional works should be carried out on traditional manufacturing process of these friction materials in order to improve the product quality and elaborate a material operating engagement in an efficient and regular manner. Besides, 3D printing process seems to be interesting and easy to investigate for clutch facings since the reduced number of parameters that monitor this additive manufacturing technique.